Radiometric dating research paper
The radiocarbon dating method is based on the fact that radiocarbon is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen.
Research has been ongoing since the 1960s to determine what the proportion of in the atmosphere has been over the past fifty thousand years.
The resulting data, in the form of a calibration curve, is now used to convert a given measurement of radiocarbon in a sample into an estimate of the sample's calendar age.
Even for the first investigation, there was a possibility of using radiocarbon dating to determine the age of the linen from which the shroud was woven.
The size of the sample then required, however, was ~500cm, which would clearly have resulted in an unacceptable amount of damage, and it was not until the development in the 1970s of small gas-counters and accelerator-mass-spectrometry techniques (AMS), requiring samples of only a few square centimetres, that radiocarbon dating of the shroud became a real possibility. The shroud was separated from the backing cloth along its bottom left-hand edge and a strip (~10 mm x 70 mm) was cut from just above the place where a sample was previously removed in 1973 for examination.
This was done by observing the relative age sequence of rock units in a given area and determining, from stratigraphic relations, which rock units are younger, which are older, and what assemblages of fossils are contained in each unit.